The pigmentary system of developing axolotls

Development ◽  
1984 ◽  
Vol 81 (1) ◽  
pp. 105-125
Author(s):  
S. K. Frost ◽  
L. G. Epp ◽  
S. J. Robinson
Keyword(s):  
Developmental Stages ◽  
Pigment Cell ◽  
Cell Types ◽  
Ambystoma Mexicanum ◽  
Pigment Cells ◽  
Wild Type ◽  
Cell Type ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Mutant Phenotypes

A biochemical and transmission electron microscopic description of the wild-type pigment phenotype in developing Mexican axolotls (Ambystoma mexicanum) is presented. There are three pigment cell types found in adult axolotl skin - melanophores, xanthophores and iridophores. Both pigments and pigment cells undergo specific developmental changes in axolotls. Melanophores are the predominant pigment cell type throughout development; xanthophores occur secondarily and in fewer numbers than melanophores; iridophores do not appear until well into the larval stage and remain thereafter as the least frequently encountered pigment cell type. Ultrastructural differences in xanthophore organelle (pterinosome) structure at different developmental stages correlate with changes in the pattern of pteridine biosynthesis. Sepiapterin, a yellow pteridine, is present in larval axolotl skin but not in adults. Ribofiavin (also yellow) is present in minimal quantities in larval skin and large quantities in adult axolotl skin. Pterinosomes undergo a morphological “reversion” at some point prior to or shortly after axolotls attain sexual maturity. Correlated with the neotenic state of the axolotl, certain larval pigmentary features are retained throughout development. Notably, the pigment cells remain scattered in the dermis such that no two pigment cell bodies overlap, although cell processes may overlap. This study forms the basis for comparison of the wild type pigment phenotype to the three mutant phenotypes-melanoid, axanthic and albino-found in the axolotl.

The pigmentary system of developing axolotls

Development ◽  
1986 ◽  
Vol 92 (1) ◽  
pp. 255-268
Author(s):  
S. K. Frost ◽  
L. G. Epp ◽  
S. J. Robinson
Keyword(s):  
Developmental Stages ◽  
Structural Characteristics ◽  
Cell Types ◽  
Ambystoma Mexicanum ◽  
Pigment Cells ◽  
Wild Type ◽  
Transmission Electron ◽  
In The Wild ◽  
Yellow Pigments ◽  
First Time

The albino mutant in the Mexican axolotl (Ambystoma mexicanum) is analysed with respect to the differentiation of pigment cells. Pigment cells were observed with the transmission electron microscope in order to determine any unusual structural characteristics and to determine what happens to each of the cell types as development proceeds. Chemical analyses of pteridine pigments were also carried out, and the pattern of pteridines in albino animals was found to be more complex than, and quantitatively enhanced (at all developmental stages examined) over, the pattern observed in comparable wild-type axolotls. The golden colour of albino axolotls is due primarily to sepiapterin (a yellow pteridine) and secondarily to riboflavin (and other flavins). Coincident with enhanced levels of yellow pigments, xanthophore pigment organelles (pterinosomes) in albino skin reach a mature state earlier than they do in wild-type axolotl skin. This morphology is conserved throughout development in albino animals whereas it is gradually lost in the wild type. Unpigmented melanophores from albino axolotls are illustrated for the first time, and in larval albino axolotls the morphology of these cells is shown to be very similar to xanthophore morphology. In older albino animals xanthophores are easily distinguished from unpigmented melanophores. Iridophores seem to appear in albino skin at an earlier stage than they have been observed in wild-type skin. Morphologically, wild-type and albino iridophores are identical.

The pigmentary system of developing axolotls

Development ◽  
1984 ◽  
Vol 81 (1) ◽  
pp. 127-142
Author(s):  
S. K. Frost ◽  
L. G. Epp ◽  
S. J. Robinson
Keyword(s):  
Structural Characteristics ◽  
Cell Types ◽  
Ambystoma Mexicanum ◽  
Pigment Cells ◽  
Similar Data ◽  
Wild Type ◽  
Transmission Electron ◽  
Pteridine Biosynthesis ◽  
Development Proceeds ◽  
Chemical Evidence

The melanoid mutant in the Mexican axolotl (Ambystoma mexicanum) is analysed with respect to the differentiation of pigment cells. Pigment cells were observed with the transmission electron microscope in order to determine any unusual structural characteristics and to determine what happens to each of the cell types as development proceeds. Chemical analysis of pteridine pigments was also carried out, and changes in pteridine biosynthesis were found to correlate well with changes in xanthophore morphology and number. In melanoid axolotls, as development proceeds, melanophore numbers increase, xanthophores decrease, and iridophores fail to differentiate at all. This is considered to result from: (a) conversion of xanthophores (that are present in young larvae) to melanophores; (b) the gradual programming of the majority of chromatoblasts to become, exclusively, melanophores, and (c) the failure of some chromatoblasts (possibly iridoblasts) to differentiate altogether. The ultrastructural and chemical evidence presented in this study is compared to similar data for wild-type axolotls, and a mechanism regarding how the melanoid gene might act is suggested.

The pigmentary system of developing axolotls

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 117-130
Author(s):  
S. K. Frost ◽  
L. G. Epp ◽  
S. J. Robinson
Keyword(s):  
Electron Micrographs ◽  
Biosynthetic Pathway ◽  
Ambystoma Mexicanum ◽  
Pigment Cells ◽  
Transmission Electron Micrographs ◽  
Electron Microscopic ◽  
Mexican Axolotl ◽  
Transmission Electron ◽  
Pteridine Biosynthesis

The axanthic mutant in the Mexican axolotl (Ambystoma mexicanum) was analysed with respect to the differentiation of pigment cells. Transmission electron micrographs revealed the presence of melanophores and cells that are described as unpigmented xanthophores in axanthic skin. Iridophores apparently failed to differentiate in axanthic axolotls (a pattern similar to that observed in melanoid axolotls). Chromatographic analyses of skin extracts confirmed that there are no pteridines (xanthophore pigments) in axanthic skin, suggesting that the axanthic gene may affect pteridine biosynthesis at some point early in the biosynthetic pathway. Why iridophores fail to differentiate in these animals is not known, but this, too, may be related to an inability to synthesize pigments properly. Xanthophore and iridophore pigments both presumably derive from purine precursors. Finally, all axanthic animals were found to be infected by a virus. Electron microscopic results demonstrated the presence of numerous macrophages in the dermis of the skin, occupying positions typical of pigment cells. The virus was localized primarily in macrophages, but was also observed in pigment cells. The virus is, as yet, uncharacterized but is thought to contribute to the low survivability of axanthic adults.

Dendritic cells of the human epidermis: immuno-electron microscopic studies of la antigen reactivity

1978 ◽  
Vol 36 (2) ◽  
pp. 644-645
Author(s):  
G. Rowden ◽  
M. G. Lewis ◽  
T. M. Phillips
Keyword(s):  
Dendritic Cells ◽  
Langerhans Cells ◽  
Cell Types ◽  
Cell Type ◽  
Electron Microscopic ◽  
La Antigen ◽  
Microscopic Studies ◽  
A Cell ◽  
C3 Receptors ◽  
Antigen Reactivity

Langerhans cells of mammalian stratified squamous epithelial have proven to be an enigma since their discovery in 1868. These dendritic suprabasal cells have been considered as related to melanocytes either as effete cells, or as post divisional products. Although grafting experiments seemed to demonstrate the independence of the cell types, much confusion still exists. The presence in the epidermis of a cell type with morphological features seemingly shared by melanocytes and Langerhans cells has been especially troublesome. This so called "indeterminate", or " -dendritic cell" lacks both Langerhans cells granules and melanosomes, yet it is clearly not a keratinocyte. Suggestions have been made that it is related to either Langerhans cells or melanocyte. Recent studies have unequivocally demonstrated that Langerhans cells are independent cells with immune function. They display Fc and C3 receptors on their surface as well as la (immune region associated) antigens.

Fine structure of the kinetochores in six species of the Coleoptera

Genome ◽  
1997 ◽  
Vol 40 (3) ◽  
pp. 379-385
Author(s):  
Klaus Werner Wolf
Keyword(s):  
Direct Contact ◽  
Karyotype Evolution ◽  
Coccinella Septempunctata ◽  
Cell Types ◽  
Male Meiosis ◽  
Serial Sections ◽  
Cell Type ◽  
Present Survey ◽  
Transmission Electron ◽  
Size Variability

Kinetochore structure was examined in a total of 6 species from 5 different families of the Coleoptera using transmission electron microscopy of ultrathin serial sections. Metaphase spermatogonia and primary and secondary spermatocytes were studied in Tenebrio molitor (Tenebrionidae) to determine whether kinetochore structure varies depending on the cell type. In all three cell types, the kinetochore microtubules (MTs) were in direct contact with the chromosomal surface, and kinetochore plates were not detectable. In the other species, only metaphase I spermatocytes were examined. As in T. molitor, distinct kinetochore plates were also absent in Adelocera murina (Elateridae), Agapanthia villosoviridescens (Cerambycidae), and Coccinella septempunctata (Coccinellidae). However, bivalents in male meiosis of two representatives of the Chrysomelidae, Agelastica alni and Chrysolina graminis, showed roughly spherical kinetochores at their poleward surfaces. Microtubules were in contact with this material. Thus, although the present survey covers only a small number of species, it is clear that at least two kinetochore types occur in the Coleoptera. The cytological findings are discussed in the context of chromosome number and genome size variability in the Coleopteran families studied. It is suggested that properties of the kinetochores could play a role in karyotype evolution in the Coleoptera.Key words: bivalent, microtubule, meiosis, metaphase, spermatocyte.

Abstract 17093: Human Neonatal Cardiac Mesenchymal Stem Cells Demonstrates Superior Cardiac Regenerative Abilities Compared to Other Stem Cells

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Muthukumar Gunasekaran ◽  
Rachana Mishra ◽  
Progyaparamita Saha ◽  
Xuebin Fu ◽  
Mohamed Abdullah ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Stem Cell ◽  
Inflammatory Cytokines ◽  
Cell Types ◽  
Wild Type ◽  
Cell Type ◽  
Anti Inflammatory ◽  
Stem Cell Type

Stem cells transplantation is being explored as an effective therapy for heart diseases. However, majority of stem cell therapies for adult patients with myocardial infarction (MI) had mixed and inconsistent results implying chronological age may influence the effectiveness of regenerative therapies. Therefore, herein, we performed a head-to-head comparison between different, well-studied stem cell types to identify the superior regenerative cell type using rodent MI model.After our standard characterization for each stem cell type (FACS for cell surface markers), 1 million neonatal Cardiac Mesenchymal Stem cells (nMSCs), adult MSCs (aMSCs), adult derived cardiosphere derived cells (aCDCs), umbilical cord derived cells (UCBCs), Bone Marrow derived Mesenchymal Stem cells (BM-MSCs), or cell-free Iscove Modified Dulbecco Medium (IMDM as placebo control) were injected into athymic rat myocardial infarct model. Although all the tested groups significantly improved ejection fraction, nMSCs outperformed other stem cells in cardiac functional recovery. Additionally, nMSCs also showed significant increased cardiac functional recovery compared to aMSCs in wild type rat MI model. Mason trichrome staining with heart sections revealed that decreased fibrosis was evident on nMSCs injection compared to aMSCs in both athymic and wild type rat MI model. Myocardial sections from rats received nMSCs showed significantly reduced M1 macrophages (inflammatory) and increased M2 macrophages (anti-inflammatory) compared with sections from rats having received aMSCs and IMDM control. Pro and anti-inflammatory cytokines analyzed on sera collected on day 2 and 7 revealed that anti-inflammatory cytokine (IL10) was significantly increased and inflammatory cytokines (IL4 and IL12) reduced in nMSCs compared to aMSCs transplanted MI rat model.In conclusion, nMSCs demonstrated superior functional abilities, reduced fibrosis, inflammatory cells and cytokines compared to all the other cell types and with aMSCs demonstrating that nMSCs is an ideal stem cell type for therapeutic application in myocardial infarction.

scholarly journals Regulation of melanocyte development by ligand-dependent BMP signaling underlies oncogenic BMP signaling in melanoma

2019 ◽  
Author(s):  
Alec K. Gramann ◽  
Arvind M. Venkatesan ◽  
Melissa Guerin ◽  
Craig J. Ceol
Keyword(s):  
Neural Crest ◽  
Pigment Cell ◽  
Terminal Differentiation ◽  
Melanoma Cells ◽  
Cell Development ◽  
Bmp Signaling ◽  
Pigment Cells ◽  
Cell Type ◽  
Neural Crest Development ◽  
Direct Regulation

AbstractPreventing terminal differentiation is important in the development and progression of many cancers including melanoma. Recent identification of the BMP ligand GDF6 as a novel melanoma oncogene showed GDF6-activated BMP signaling suppresses differentiation of melanoma cells. Previous studies have identified roles for GDF6 orthologs during early embryonic and neural crest development, but have not identified direct regulation of melanocyte development by GDF6. Here, we investigate the BMP ligand gdf6a, a zebrafish ortholog of human GDF6, during the development of melanocytes from the neural crest. We establish that the loss of gdf6a or inhibition of BMP signaling during neural crest development disrupts normal pigment cell development, leading to an increase in the number of melanocytes and a corresponding decrease in iridophores, another neural crest-derived pigment cell type in zebrafish. This shift occurs as pigment cells arise from the neural crest and depends on mitfa, an ortholog of MITF, a key regulator of melanocyte development that is also targeted by oncogenic BMP signaling. Together, these results indicate that the oncogenic role ligand-dependent BMP signaling plays in suppressing differentiation in melanoma is a reiteration of its physiological roles during melanocyte development.

nacre encodes a zebrafish microphthalmia-related protein that regulates neural-crest-derived pigment cell fate

Development ◽  
1999 ◽  
Vol 126 (17) ◽  
pp. 3757-3767 ◽  
Author(s):  
J.A. Lister ◽  
C.P. Robertson ◽  
T. Lepage ◽  
S.L. Johnson ◽  
D.W. Raible
Keyword(s):  
Transcription Factor ◽  
Retinal Pigment Epithelium ◽  
Neural Crest ◽  
Cell Fate ◽  
Pigment Cell ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Pigment Cells ◽  
Evolutionary Divergence ◽  
Wild Type

We report the isolation and identification of a new mutation affecting pigment cell fate in the zebrafish neural crest. Homozygous nacre (nac(w2)) mutants lack melanophores throughout development but have increased numbers of iridophores. The non-crest-derived retinal pigment epithelium is normal, suggesting that the mutation does not affect pigment synthesis per se. Expression of early melanoblast markers is absent in nacre mutants and transplant experiments suggested a cell-autonomous function in melanophores. We show that nac(w2) is a mutation in a zebrafish gene encoding a basic helix-loop-helix/leucine zipper transcription factor related to microphthalmia (Mitf), a gene known to be required for development of eye and crest pigment cells in the mouse. Transient expression of the wild-type nacre gene restored melanophore development in nacre(−/−) embryos. Furthermore, misexpression of nacre induced the formation of ectopic melanized cells and caused defects in eye development in wild-type and mutant embryos. These results demonstrate that melanophore development in fish and mammals shares a dependence on the nacre/Mitf transcription factor, but that proper development of the retinal pigment epithelium in the fish is not nacre-dependent, suggesting an evolutionary divergence in the function of this gene.

scholarly journals A community-based transcriptomics classification and nomenclature of neocortical cell types

2020 ◽  
Vol 23 (12) ◽  
pp. 1456-1468 ◽  
Author(s):  
Rafael Yuste ◽  
Michael Hawrylycz ◽  
Nadia Aalling ◽  
Argel Aguilar-Valles ◽  
Detlev Arendt ◽  
...  
Keyword(s):  
Data Aggregation ◽  
Developmental Stages ◽  
Cell Types ◽  
The Body ◽  
Cortical Circuits ◽  
Cell Type ◽  
Community Based ◽  
Cortical Cells ◽  
Molecular Features ◽  
Definition Of

AbstractTo understand the function of cortical circuits, it is necessary to catalog their cellular diversity. Past attempts to do so using anatomical, physiological or molecular features of cortical cells have not resulted in a unified taxonomy of neuronal or glial cell types, partly due to limited data. Single-cell transcriptomics is enabling, for the first time, systematic high-throughput measurements of cortical cells and generation of datasets that hold the promise of being complete, accurate and permanent. Statistical analyses of these data reveal clusters that often correspond to cell types previously defined by morphological or physiological criteria and that appear conserved across cortical areas and species. To capitalize on these new methods, we propose the adoption of a transcriptome-based taxonomy of cell types for mammalian neocortex. This classification should be hierarchical and use a standardized nomenclature. It should be based on a probabilistic definition of a cell type and incorporate data from different approaches, developmental stages and species. A community-based classification and data aggregation model, such as a knowledge graph, could provide a common foundation for the study of cortical circuits. This community-based classification, nomenclature and data aggregation could serve as an example for cell type atlases in other parts of the body.

scholarly journals Hemicentin-1 is an essential extracellular matrix component of the dermal–epidermal and myotendinous junctions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniela Welcker ◽  
Cornelia Stein ◽  
Natalia Martins Feitosa ◽  
Joy Armistead ◽  
Jin-Li Zhang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Developmental Stages ◽  
Cell Types ◽  
Connective Tissues ◽  
Functional Behavior ◽  
Transmission Electron ◽  
Cellular Microenvironments ◽  
And Function ◽  
Myotendinous Junctions

AbstractThe extracellular matrix architecture is composed of supramolecular fibrillar networks that define tissue specific cellular microenvironments. Hemicentins (Hmcn1 and Hmcn2) are ancient and very large members (> 600 kDa) of the fibulin family, whose short members are known to guide proper morphology and functional behavior of specialized cell types predominantly in elastic tissues. However, the tissue distribution and function of Hemicentins within the cellular microenvironment of connective tissues has remained largely unknown. Performing in situ hybridization and immunofluorescence analyses, we found that mouse Hmcn1 and Hmcn2 show a complementary distribution throughout different tissues and developmental stages. In postnatal dermal–epidermal junctions (DEJ) and myotendinous junctions (MTJ), Hmcn1 is primarily produced by mesenchymal cells (fibroblasts, tenocytes), Hmcn2 by cells of epithelial origin (keratinocytes, myocytes). Hmcn1−/− mice are viable and show no overt phenotypes in tissue tensile strength and locomotion tests. However, transmission electron microscopy revealed ultrastructural basement membrane (BM) alterations at the DEJ and MTJ of Hmcn1−/− mice, pointing to a thus far unknown role of Hmcn1 for BM and connective tissue boundary integrity.

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